This invention relates to the field of interconnect wiring of high-speed integrated circuit chips. More particularly, it relates to the formation of low dielectric constant films through the use of nanoparticles formed with rigid connector compounds.
In order to increase the speed of microelectronic integrated circuits, both the size of the wiring features and the spacing between adjacent wires must be reduced. One critical area in need of advancement in order to simultaneously reduce the size and spacing of the wiring features, and maintain a high speed of signal propagation is the dielectric material used between the metal interconnects of the integrated circuit. For example, for a given film wire resistance R, the speed of the interconnect signal varies as 1/RC, where C is the capacitance between wires. Using a low dielectric constant film (low-k dielectric) makes C smaller and hence increases the speed of the circuit. Films with dielectric constants in the range of 2-3 will be needed within 2 years for future high-speed integrated circuits.
In addition, as distances between circuit elements become smaller, there are increased problems due to capacitive coupling and induced propagation delays. One way to reduce these difficulties is through the use of low-k dielectrics. Low-k dielectrics lower line capacitance of the interconnects.
U.S. Pat. No. 5,801,092 to Ayers describes a method of forming a dielectric film utilizing silicon dioxide nanospheres. A non-polar organic coating surrounds the silicon dioxide nanospheres. Ayers utilizes these organic coated nanospheres to form a porous dielectric film. The more porous the film, the lower its dielectric constant. The silicon dioxide particles are made by the hydrolysis and condensation reactions of tetraethylorthosilicate, (TEOS), as the precursor molecule. The non-polar organic film used in Ayers consists of fluoroalkylsilane compounds. The fluoroalkylsilane compounds only bind to the nanoparticle at one end and are very flexible.
One problem with the nanosphere particles in Ayers is that the core dielectric material is made up of silicon dioxide, which has a relatively high dielectric constant of about 4. The silicon dioxide core material limits the reduction of the dielectric constant of the porous film. Another problem in Ayers is that the organic film is flexible and binds the nanospheres at only one site. When a dielectric film is formed by these organic coated nanospheres, the flexible organic compounds compress and the spaces between the nanospheres are reduced. The film structure formed is only slightly porous resulting in a higher dielectric constant film. In addition, since the organic films are flexible, variability of compression can change the porosity of the film, resulting in a non-reproducible dielectric constant film.
It is thus an object of the present invention to provide a nanometer scale particle that has a lower dielectric constant than silicon dioxide and can be used in the formation of a low-k dielectric film.
It is another object of the present invention to provide a rigid connector compound between particles that resists compression, resulting in a more reproducible, porous and lower dielectric constant film.
It is also an object of the present invention to provide a fabrication method using the novel dielectric particle and/or rigid connector compounds to form a low-k dielectric film.
The present invention relates to a novel organosilicon particle having the formula SiaObCcHd. The particle may be coated with an organic film, preferably a rigid connector compound. The present invention also provides a method of using the organosilicon particle and/or rigid connector compound in the formation of a low-k dielectric film.